1. A study amongst schoolboys in villages around Hyderabad, India, showed that almost all the boys had riboflavin deficiency, 61% had pyridoxine deficiency, and 9.4% had thiamin deficiency as judged by enzymic tests.
2. The prevalence of angular stomatitis was 41.3% and that of glossitis was 18.2%. Biochemical deficiency of riboflavin and pyridoxine was marginally higher in children with angular stomatitis with or without associated glossitis, than in children without oral lesions.
3. Treatment with B-complex vitamins (containing 4 mg riboflavin and 10 mg pyridoxine) daily for 1 month produced significant reduction in the prevalence of glossitis but had no effect on angular stomatitis. The latter responded to topical application of gentian violet.
4. Small but significant changes in erythrocyte enzymes occurred over the period of 1 month even without vitamin supplements.
5. Results suggest that while glossitis is a relatively early manifestation of riboflavin or pyridoxine deficiency or both, angular stomatitis has a more complex aetiology perhaps associated with infection.